Event Horizon Telescope Captures Never-Before-Seen Detail of Black Hole Jets
Two years ago, scientists working with the Event Horizon Telescope (EHT) made history by releasing the first-ever photo of a black hole. The image confirmed many of our ideas about these massive collapsed stars, but the team didn’t stop there. The latest data release focuses on a different target, an active galaxy known as Centaurus A. You’ve probably seen images of Centaurus A in the past — it’s one of the brightest galaxies in the sky. You’ve never seen it like this, though.
The Event Horizon Telescope is not a single instrument. It is composed of radio telescopes scattered around the globe. By observing the same object with each telescope, scientists are able to combine the data using atomic clock timestamps and lots of supercomputer cycles. It takes months to assemble EHT images, but the results are staggering. We could have never seen the black hole in M87 with a single telescope, and we’ve never seen Centaurus A in such detail, either.
Centaurus A is of note because it has an active galactic nucleus. The black hole in the center is busy chowing down on matter while blasting a relativistic jet out into deep space. That makes Centaurus A the closest galaxies that are bright in radio frequencies. It’s the fifth brightest galaxy in the sky overall, making it a common target for amateur astronomers.
The image above is one of many taken of Centaurus A in the past. The EHT images aren’t as visually arresting until you understand what these blobs are. As seen below, the EHT was able to zoom in on the jet of plasma escaping from the galactic nucleus. Despite being 10 million light-years away, the team was able to examine the structure of the jet in amazing detail.
These images of the jet are 16 times sharper than any previous observation. The data appears to show that only the edge of the stream is glowing. Some past analyses of other black hole jets have suggested this tube-like structure, but now we have more confirmation. The reason is unclear, but it may be due to the edges interacting with stationary gas clouds, which causes them to heat up and glow.
Observations closer to the black hole show the tube narrowing into a cone, but the base is still very wide. That could mean the black hole’s accretion disk is the source, but some scientists believe these jets must be utilizing the rotational energy of the black hole to explode outward with such force. The EHT hasn’t answered all the questions scientists have about black holes, but it might point us in the right direction.